Photovoltaic power generation system

ABSTRACT

A photovoltaic power generation system is discussed. The photovoltaic power generation system includes a solar cell module including a plurality of solar cell groups divided into groupings of the plurality of solar cell groups, each of the plurality of solar cell groups including at least one of one solar cell row which a plurality of solar cells are electrically connected, and a plurality of signal control units connected to the plurality of solar cell groups, respectively, wherein the each of the plurality of signal control units track a maximum power based on the current and the voltage output from each of the plurality of solar cell groups and outputs the maximum power.

This application is a continuation of co-pending U.S. application Ser.No. 13/051,600 filed on Mar. 18, 2011, which claims priority to and thebenefit of Korean Patent Application No. 10-2010-0025722 filed in theKorean Intellectual Property Office on Mar. 23, 2010. The contents ofall of these applications are hereby incorporated by reference as fullyset forth herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Example embodiments of the invention relate to a photovoltaic powergeneration system.

2. Description of the Related Art

Recently, as existing energy sources such as petroleum and coal areexpected to be depleted, interests in renewable energy sources forreplacing the existing energy sources are increasing. Among therenewable energy sources, solar cells for generating electric energyfrom solar energy have been particularly spotlighted.

A solar cell generally includes a substrate and an emitter layer, eachof which is formed of a semiconductor, and electrodes respectivelyformed on the substrate and the emitter layer. The semiconductorsforming the substrate and the emitter layer have different conductivetypes, such as a p-type and an n-type. A p-n junction is formed at aninterface between the substrate and the emitter layer.

When light is incident on the solar cell, a plurality of electron-holepairs are generated in the semiconductors. The electron-hole pairs areseparated into electrons and holes by the photovoltaic effect. Thus, theseparated electrons move to the n-type semiconductor (e.g., the emitterlayer) and the separated holes move to the p-type semiconductor (e.g.,the substrate), and then the electrons and holes are collected by theelectrodes electrically connected to the emitter layer and thesubstrate, respectively. The electrodes are connected to each otherusing electric wires to thereby obtain electric power.

The solar cell may be individually used, or the plurality of solar cellshaving the same structure may be connected in series or in parallel toone another to manufacture a solar cell module for efficient use andeasy installation. Accordingly, a desired number of solar cell modulesmay be connected to one another to manufacture a module array, i.e., asolar cell panel. A user may obtain electric power from the solar cellpanel.

SUMMARY OF THE INVENTION

In one aspect, there is a photovoltaic power generation system includinga solar cell module having a plurality of solar cell row groups, aplurality of sensing units respectively connected to the plurality ofsolar cell row groups, each of the plurality of sensing units beingconnected to a corresponding solar cell row group, and being configuredto sense a signal output from the corresponding solar cell row group andoutput a sensing signal, a plurality of amplification units respectivelyconnected to the plurality of solar cell row groups, and a signalcontrol unit configured to detect amounts of currents output from theplurality of solar cell row groups in response to the sensing signalsoutput from the plurality of sensing units, control a plurality ofcontrol signals respectively applied to the plurality of amplificationunits based on the detected amounts of currents, track a maximum powerbased on a voltage and a current output from the solar cell module, andoutput the maximum power, wherein each of the plurality of amplificationunits is connected to the corresponding solar cell row group, andamplifies a current to a predetermined amplification level determinedbased on one of the plurality of control signals from the signal controlunit and applies the amplified current to an input terminal of thecorresponding solar cell row group.

Each of the plurality of sensing units may sense the signal as an amountof current output from the corresponding solar cell row group.

The signal control unit may read the amount of current sensed by each ofthe plurality of sensing units, compare the amount of sensed currentwith a setting value, and control the control signal applied to each ofthe plurality of amplification units based on a difference between theamount of sensed current and the setting value.

The signal control unit may increase a magnitude of each control signalas the difference between the amount of sensed current and the settingvalue increases.

Each of the plurality of control signals may be a voltage.

Each of the plurality of solar cell row groups may have at least one rowof solar cells.

The plurality of solar cell row groups may be connected in series to oneanother.

In one aspect, there is a photovoltaic power generation system includinga solar cell module having a plurality of solar cell row groups, aplurality of sensing units respectively connected to the plurality ofsolar cell row groups, each of the plurality of sensing units beingconnected to a corresponding solar cell row group, and being configuredto sense a signal output from the corresponding solar cell row group andoutput a sensing signal, a plurality of amplification units respectivelyconnected to the plurality of solar cell row groups, and a plurality ofsignal control units, each of which is connected to a correspondingsensing unit, to a corresponding amplification unit, and to thecorresponding solar cell row group, and is configured to detect anamount of current output from the corresponding solar cell row group inresponse to the sensing signal output from the corresponding sensingunit, track a maximum power based on a voltage and a current output fromthe corresponding amplification unit or the corresponding solar cell rowgroup based on the detected amount of the current, and output themaximum power, wherein each of the plurality of amplification units isconnected to the corresponding solar cell row group, and amplifies acurrent to a predetermined amplification level determined based on acontrol signal from the corresponding signal control unit and appliesthe amplified current to an input terminal of the corresponding solarcell row group.

When each of the plurality of signal control units determines that thecorresponding solar cell row group is outputting less than a particularamount of current based on the sensing signal from the correspondingsensing unit, each of the plurality of signal control units may trackthe maximum power using the current and the voltage output from thecorresponding amplification unit and may output the maximum power.

Each of the plurality of sensing units may sense the signal as an amountof current output from the corresponding solar cell row group.

Each of the plurality of signal control units may read the amount ofcurrent sensed by the corresponding sensing unit, compares the amount ofsensed current with a setting value, and may control the control signalapplied to a corresponding amplification unit based on a differencebetween the amount of sensed current and the setting value.

Each of the plurality of signal control units may increase a magnitudeof the corresponding control signal as the difference between the amountof sensed current and the setting value increases.

Each of the control signals may be a voltage.

Each of the plurality of solar cell row groups may have a plurality ofsolar cells connected in series to one another.

In one aspect, there is a photovoltaic power generation system includinga solar cell module having a plurality of solar cell row groups, aplurality of signal control units respectively connected to theplurality of solar cell row groups, each of the plurality of signalcontrol units being connected to a corresponding solar cell row groupand being configured to track a maximum power based on a current and avoltage output from the corresponding solar cell row group and outputthe maximum power, and a final power output unit configured to select alargest power among the maximum powers output from the plurality ofsignal control units as a final power and output the final power.

In one aspect, there is a photovoltaic power generation system includinga plurality of solar cell modules each including a plurality of solarcells, a plurality of signal control units respectively connected to theplurality of solar cell modules, each of the plurality of signal controlunits being connected to a corresponding solar cell module and beingconfigured to track a maximum power based on a current and a voltageoutput from the corresponding solar cell module and output the maximumpower, and a final power output unit configured to select a largestpower among the maximum powers output from the plurality of signalcontrol units as a final power and output the final power.

In one aspect, there is a photovoltaic power generation system includinga plurality of solar cell modules each including a plurality of solarcells, a plurality of amplification units respectively connected to theplurality of solar cell modules, each of the plurality of amplificationunits being connected to a corresponding solar cell module and beingconfigured to amplify a voltage output from the corresponding solar cellmodule connected to each amplification unit to a predeterminedmagnitude, a plurality of signal control units respectively connected tothe plurality of solar cell modules and the plurality of amplificationunits, each of the plurality of signal control units being connected tothe corresponding solar cell module, being connected to a correspondingamplification unit, and being configured to track a maximum power basedon a current output from the corresponding solar cell module, theamplified voltage output from the corresponding amplification unit andoutput the maximum power, and a final power output unit configured toselect a largest power among the maximum powers output from theplurality of signal control units as a final power and output the finalpower.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a schematic block diagram of a photovoltaic power generationsystem according to an example embodiment of the invention;

FIG. 2 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention;

FIG. 3 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention;

FIG. 4 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention; and

FIG. 5 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention will be described more fully hereinafter with reference tothe accompanying drawings, in which example embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the embodiments setforth herein.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present. Further, it will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “entirely” on another element, it may be on the entire surface ofthe other element and may not be on a portion of an edge of the otherelement.

Reference will now be made in detail to embodiments of the invention,examples of which are illustrated in the accompanying drawings.

FIG. 1 is a schematic block diagram of a photovoltaic power generationsystem according to an example embodiment of the invention.

As shown in FIG. 1, a photovoltaic power generation system 100 accordingto an example embodiment of the invention includes a solar cell module10, a plurality of sensing units 21 to 23 connected to the solar cellmodule 10, a plurality of amplification units 31 to 33 connected to thesolar cell module 10, and a signal control unit 70 connected to theplurality of sensing units 21 to 23 and the plurality of amplificationunits 31 to 33.

The solar cell module 10 includes a plurality of solar cells 1, and theplurality of solar cells 1 are connected in series to one another usingelectron electrodes and hole electrodes. Such series connected pluralityof solar cells 1 may be referred to as a solar cell row group. AlthoughFIG. 1 illustrates the solar cells 1 having a structure of a 10×4matrix, the number of solar cells 10 may increase or decrease, and maydiffer, if necessary or desired.

The plurality of sensing units 21-23 include the first to third sensingunits 21 to 23. Each of the sensing units 21-23 is connected between twoadjacent rows of solar cells 1 and the signal control unit 70. Morespecifically, as shown in FIG. 1, an input terminal of the first sensingunit 21 is connected between the first and second rows of solar cells 1,and an output terminal of the first sensing unit 21 is connected to thesignal control unit 70. An input terminal of the second sensing unit 22is connected between the second and third rows of solar cells 1, and anoutput terminal of the second sensing unit 22 is connected to the signalcontrol unit 70. An input terminal of the third sensing unit 23 isconnected between the third and fourth rows of solar cells 1, and anoutput terminal of the third sensing unit 23 is connected to the signalcontrol unit 70.

Each of the sensing units 21-23 receives a signal output from a previousrow to a next row of the two adjacent rows of solar cells 1.

As above, because each of the sensing units 21-23 is positioned betweenthe two adjacent rows of the solar cells 1, the number of sensing unitsmay vary depending on the number of solar cell rows arranged in thesolar cell module 10.

Each of the sensing units 21-23 senses (detects or determines) signals(for example, current) received from each of the two adjacent rows ofsolar cells connected to each sensing unit and outputs a sensing signalcorresponding to an amount of sensed signals (for example, an amount ofsensed current) to the signal control unit 70.

The plurality of amplification units 31-33 include the first to thirdamplification units 31 to 33. Each of the amplification units 31-33 isconnected between the two adjacent rows of solar cells 1 and the signalcontrol unit 70. More specifically, as shown in FIG. 1, an inputterminal of the first amplification unit 31 is connected between thefirst and second rows of solar cells 1, and an output terminal of thefirst amplification unit 31 is connected to the signal control unit 70.An input terminal of the second amplification unit 32 is connectedbetween the second and third rows of solar cells 1, and an outputterminal of the second amplification unit 32 is connected to the signalcontrol unit 70. An input terminal of the third amplification unit 33 isconnected between the third and fourth rows of solar cells 1, and anoutput terminal of the third amplification unit 33 is connected to thesignal control unit 70. The first to third amplification units 31-33 maybe disposed opposite the corresponding first to third sensing units21-23, respectively, in an alternating manner. For example, as shown inFIG. 1, the first amplification unit 31 may be disposed on one sidebetween the first and second rows of solar cells 1, and the firstsensing unit 21 may be disposed on the other side between the first andsecond rows of solar cells 1. A relationship between the sensing units21-23 and the amplification units 31-33 may vary.

The first to third amplification units 31-33 receive control signalsCS1-CS3 from the signal control unit 70, respectively. Hence, operationsof the first to third amplification units 31-33 may vary depending onthe control signals CS1-CS3. Each of the first to third amplificationunits 31-33 amplifies a signal applied to its input terminal to apredetermined amplification level and outputs the amplified signal toits output terminal. The amplification level of each of the first tothird amplification units 31-33 may vary depending on magnitudes of thecontrol signals CS1-CS3.

The signal control unit 70 controls the magnitudes of the controlsignals CS1-CS3 applied to the first to third amplification units 31-33based on the sensing signals from the first to third sensing units21-23. The signal control unit 70 senses electric power generated in thesolar cell module 10.

An operation of the photovoltaic power generation system 100 having theabove-described structure is described below.

When solar light is incident on the solar cell module 10, electrons andholes corresponding to an amount of incident solar light are produced bythe operation of each solar cell 1 of the solar cell module 10. Theelectrons and holes move to the solar cells 1, that are connected inseries to one another using electron electrodes and hole electrodes.Hence, the current and the voltage each having a predetermined magnitudeare generated in the adjacent rows of solar cells 1 and the solar cells1 connected in series to one another in zigzag, or an alternatingmanner. For example, a voltage of about 0.5 V and a current of about 8 Aare generated in each solar cell 1.

The first to third sensing units 21-23 sense the current flowing in eachof the rows of solar cells 1. In other words, the first sensing unit 21senses the current flowing in the first row of solar cells 1, the secondsensing unit 22 senses the current flowing in the second row of solarcells 1, and the third sensing unit 23 senses the current flowing in thethird row of solar cells 1. Each of the first to third sensing units21-23 outputs the sensing signal having a magnitude corresponding to theamount of sensed current to the signal control unit 70.

When the serial connection between the solar cells 1 arranged in atleast one of the rows is severed (or disconnected) or a shade phenomenon(or shading) occurs, in which at least one of the solar cells 1 arrangedin at least one of the rows is covered by a pollution material (ordebris) such as leaves, dust, and soil, the disconnected or shaded solarcells 1 cannot perform a normal energy generation operation, such asproducing a particular amount or level of energy. Thus, when at leastone of the solar cells 1 arranged in at least one of the rows isdisconnected or shaded, an amount of current output from thedisconnected or shaded solar cell 1 is reduced because the plurality ofsolar cells 1 are connected in series to one another. A reduced amountof current may vary depending on degrees of the shade and thedisconnection of the solar cell 1.

For example, when the shade phenomenon is generated in one solar cell 1arranged in the first row, the current generated in the one shaded solarcell 1 may be reduced to about 4 A. In this instance, because a voltageoutput from each of the solar cells 1 belonging to the first row isuniformly about 0.5 V, the total voltage output from the solar cells 1belonging to the first row is 5V (=0.5×10 (the number of solar cellsbelonging to the first row)). However, the current output from the firstrow is reduced from about 8 A to about 4 A. Hence, the voltage and thecurrent output from the solar cell module 10 are about 20V (=5V×4 (thenumber of solar cell rows)) and about 4 A, respectively. As a result,the power output from the solar cell module 10 is about 80 W (=20V×4 A)which is lower than about 160 W (=20V×8 A) obtained in a normaloperation of the solar cells 1.

Accordingly, the signal control unit 70 senses an amount of currentflowing in each solar cell row using the sensing signals output from thefirst to third sensing units 21-23, so as to decide (or determine) alocation of the solar cell row including the disconnected or shadedsolar cell and a reduced amount of current. For this, the signal controlunit 70 reads the sensing signals output from the first to third sensingunits 21-23 to decide (or determine) the amount of current sensed ineach solar cell row. Further, the signal control unit 70 compares theamount of sensed current with an amount of current in the normal stateto decide (or determine) the solar cell row including the solar cellthat is abnormally operating (or outputting a lower amount of currentthan a particular amount).

For example, when the signal control unit 70 reads the sensing signaloutput from the first sensing unit 21 as an abnormal signal (or below acertain amount), the signal control unit 70 decides that the at leastone disconnected or shaded solar cell is included in the first row. Whenthe signal control unit 70 reads the sensing signal output from thesecond sensing unit 22 as an abnormal signal, the signal control unit 70decides that the at least one disconnected or shaded solar cell isincluded in the second row. When the signal control unit 70 reads thesensing signal output from the third sensing unit 22 as an abnormalsignal, the signal control unit 70 decides that the at least onedisconnected or shaded solar cell is included in the third row.

Next, the signal control unit 70 outputs one or more of the controlsignals CS1-CS3 to the respective first to third amplification units31-33 depending on the signals from the one or more of the sensing units21-23. The magnitude of each of the control signals CS1-CS3, forexample, the voltage magnitude, may vary depending on the magnitude ofeach of the sensing signals output from the first to third sensing units21-23. For example, as the magnitudes of the sensing signals output fromthe first to third sensing units 21-23 increase (i.e., as the amount ofcurrent flowing in the solar cell row corresponding to each of the firstto third sensing units 21-23 increases), the magnitudes of the controlsignals CS1-CS3 respectively corresponding to the first to thirdamplification units 31-33 decrease.

In the embodiment, each of the first to third amplification units 31-33may be an amplifier including a transistor, etc. The amplification levelof the signal (for example, the current) output from the input terminalto the output terminal of each of the first to third amplification units31-33 may vary depending on the control signals CS1-CS3 respectivelyapplied to the output terminals of the first to third amplificationunits 31-33. Accordingly, each of the first to third amplification units31-33 amplifies the current applied to the input terminal thereof basedon the magnitude of each of the control signals CS1-CS3 and outputs theamplified current to the output terminal thereof.

For example, when the at least one problem solar cell (for example, theat least one disconnected or shaded solar cell) is included in the firstsolar cell row, the signal control unit 70 determines the magnitude ofthe first control signal CS1 based on the reduced amount of currentdecided (or determined) by the sensing signal from the first sensingunit 21. The signal control unit 70 then outputs the first controlsignal CS1 having the magnitude corresponding to the reduced amount ofcurrent to the first amplification unit 31. Thus, the firstamplification unit 31 amplifies the current applied to the first solarcell row to (or based on) the magnitude of the first control signal CS1and then applies the amplified current to the second solar cell row. Inthe same manner as the first solar cell row, when the at least oneproblem solar cell is included in the second solar cell row, the signalcontrol unit 70 outputs the second control signal CS2 having themagnitude determined by the sensing signal from the second sensing unit22 to the second amplification unit 32. Hence, the second amplificationunit 32 amplifies the current applied to the second solar cell row to(or based on) the magnitude of the second control signal CS2 and thenapplies the amplified current to the third solar cell row. In the samemanner as the first solar cell row, when the at least one problem solarcell is included in the third solar cell row, the signal control unit 70outputs the third control signal CS3 having the magnitude determined bythe sensing signal from the third sensing unit 23 to the thirdamplification unit 33. Hence, the third amplification unit 33 amplifiesthe current applied to the third solar cell row to (or based on) themagnitude of the third control signal CS3 and then applies the amplifiedcurrent to the fourth solar cell row. In this instance, because theamplification unit related to the solar cell row not including theproblem solar cell does not operate, the current sequentially passesthrough all of the solar cells 1 included in each row and normallyflows.

As above, even if the solar cell row including the at least one problemsolar cell exists in the solar cell module 10, the amplification units31-33 compensate for the reduced amount of current through theamplification operation. Therefore, because the power output from thesolar cell module 10 increases in proportion to the amount ofcompensated current, the output efficiency of the solar cell module 10is improved.

When the power is generated in the solar cell module 10 through such acurrent compensation operation, an output amount of power of the solarcell module 10 may vary depending on time or season. The power generatedin each solar cell 1 may vary depending on an amount of incident light.For example, an amount of power produced when an intensity of light isthe strongest in a day may be the maximum amount of power produced in aday. Further, an amount of power produced in summer, in which anintensity of light is stronger than other seasons and sunshine hours arelonger than other seasons, may be more than other seasons.

Accordingly, the signal control unit 70 performs a maximum power pointtracking (MPPT) control operation for tracking a maximum power among thepowers generated in the solar cell module 10.

For example, the signal control unit 70 detects in real-time analogsignal type current and analog signal type voltage generated in thesolar cell module 10 at each sampling time. The signal control unit 70converts the analog signal type current and voltage into digital signaltype current and voltage and calculates power using the digital signaltype current and the digital signal type voltage. Then, the signalcontrol unit 70 compares a previous power calculated at a previoussampling time with a current power calculated at a current sampling timeand selects the largest power among the previous power and the currentpower. In other words, the signal control unit 70 calculates the currentpower at each sampling time, compares the previous power with thecurrent power, and detects a maximum power point. The signal controlunit 70 selects the maximum power point as a final power (or finaloutput power) of the solar cell module 10 and outputs the final power toa subsequent device including a digital-to-analog converter (DAC), acapacitor, etc.

In the embodiment, the first to third sensing units 21-23 and the firstto third amplification units 31-33 sense the amount of current of eachsolar cell row, and the signal control unit 70 controls the operation ofthe first to third amplification units 31-33 based on the sensed amountof current. Alternatively, the sensing unit and the amplification unitmay be installed in each of solar cell row groups each including two ormore solar cell rows.

FIG. 2 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention.Structures and components identical or equivalent to those illustratedin FIG. 1 are designated in FIG. 2 with the same reference numerals, anda further description may be briefly made or may be entirely omitted.

A photovoltaic power generation system 100 a shown in FIG. 2 has thestructure similar to the photovoltaic power generation system 100 shownin FIG. 1. More specifically, the photovoltaic power generation system100 a includes a solar cell module 10 including a plurality of solarcells 1, a plurality of sensing units 211 and 212 connected to the solarcell module 10, a plurality of amplification units 311 and 312 connectedto the solar cell module 10, and a plurality of signal control units 711and 712 connected to the plurality of sensing units 211 and 212 and theplurality of amplification units 311 and 312.

On the other hand, unlike the photovoltaic power generation system 100shown in FIG. 1 in which all of the solar cells 1 included in the solarcell module 10 are connected in series to one another, in thephotovoltaic power generation system 100 a shown in FIG. 2, a pluralityof solar cell rows are divided into a plurality of solar cell row groupsGP1 and GP2 each including a predetermined number of solar cell rows,for example, two solar cell rows. Further, the solar cells 1 belongingto each of the solar cell row groups GP1 and GP2 are connected in seriesto one another, but the solar cells 1 belonging to the first solar cellrow group GP1 are electrically separated from the solar cells 1belonging to the second solar cell row group GP2.

Accordingly, the plurality of sensing units 211 and 212 and theplurality of amplification units 311 and 312 are connected to thecorresponding solar cell row groups GP1 and GP2. More specifically, asshown in FIG. 2, the first sensing unit 211 is positioned between anoutput terminal of the first solar cell row group GP1 and the firstsignal control unit 711, and the second sensing unit 212 is positionedbetween an output terminal of the second solar cell row group GP2 andthe second signal control unit 712. Further, the first amplificationunit 311 is positioned between an input terminal of the first solar cellrow group GP1 and the first signal control unit 711, and the secondamplification unit 312 is positioned between an input terminal of thesecond solar cell row group GP2 and the second signal control unit 712.

As described above, the first signal control unit 711 is connected tothe first solar cell row group GP1, the first sensing units 211, and thefirst amplification units 311. The second signal control unit 712 isconnected to the second solar cell row group GP2, the second sensingunits 212, and the second amplification units 312.

The number of solar cell row groups may vary depending on the number ofsolar cell rows belonging to one solar cell module 10, and the number ofsolar cell rows belonging to one solar cell row group may increase ordecrease, if necessary or desired. Thus, the number of sensing units andthe number of amplification units may vary depending on the number ofsolar cell row groups.

The photovoltaic power generation system 100 a according to theembodiment of the invention further includes a final power output unit80 connected to the first and second signal control units 711 and 712.

The final power output unit 80 selects the largest power among maximumpowers P1 and P2 respectively applied to the first and second signalcontrol units 711 and 712 as a final power Pmax and outputs the finalpower Pmax to a subsequent device.

An operation of the photovoltaic power generation system 100 a havingthe above-described structure is described below.

Operations of the solar cells 1 belonging to the first solar cell rowgroup GP1, the first sensing unit 211, the first amplification unit 311,and the first signal control unit 711 are substantially the same asoperations of the solar cells 1 belonging to the second solar cell rowgroup GP2, the second sensing unit 211, the second amplification unit312, and the second signal control unit 712. Therefore, only theoperations related to the first solar cell row group GP1 are describedin the embodiment of the invention, and a further description of theoperations related to the second solar cell row group GP2 may be brieflymade or may be entirely omitted.

When each of the solar cells 1 of the solar cell module 10 operatesthrough the incidence of solar light to generate voltage and currenteach having the corresponding magnitude, the first sensing unit 211senses an amount of current flowing in the first solar cell row groupGP1 and outputs the sensed amount of current to the first signal controlunit 711.

The first signal control unit 711 controls a magnitude of a controlsignal CS1 applied to the first amplification unit 311 in response to asensing signal from the first sensing unit 211. As described above withreference to FIG. 1, the first signal control unit 711 controls themagnitude of the first control signal CS1 based on the reduced amount ofcurrent decided by the sensing signal from the first sensing unit 21 andcontrols the operation of the first amplification unit 311 using thefirst control signal CS1. For example, as the reduced amount of currentof the first solar cell row group GP1 increases compared with an amountof current obtained when the solar cells 1 belonging to the first solarcell row group GP1 normally operate without the disconnection or theshade phenomenon, the magnitude of the first control signal CS1increases. Hence, an amplification level of the first amplification unit311 increases. As the reduced amount of current of the first solar cellrow group GP1 decreases, the magnitude of the first control signal CS1decreases. Hence, the amplification level of the first amplificationunit 311 decreases. When the amount of current obtained when the solarcells 1 of the first solar cell row group GP1 normally operate issubstantially equal to an amount of sensed current (i.e., when thereduced amount of current is about zero), the first signal control unit711 blocks the output (or does not output) of the first control signalCS1 to thereby stop the operation of the first amplification unit 311.

When the first amplification unit 311 operates in response to the firstcontrol signal CS1, the first signal control unit 711 decides that thefirst amplification unit 311 is in an operation state so as tocompensate for a reduction in the amount of current resulting from theabnormal operation of at least one solar cell 1 of the first solar cellrow group GP1. Thus, the first signal control unit 711 reads a signaloutput through a path {circle around (1)} passing through the firstamplification unit 311 as the current of the first solar cell row groupGP1. In this instance, the voltage output from the first amplificationunit 311 is already determined to be substantially equal to the voltageapplied to an output terminal of the first solar cell row group GP1.

On the other hand, when the first amplification unit 311 does notoperate, the first signal control unit 711 decides that all of the solarcells 1 of the first solar cell row group GP1 normally operate. Thus,the first signal control unit 711 reads the current and the voltageapplied through a path {circle around (2)} passing through the outputterminal of the first solar cell row group GP1.

Next, the first signal control unit 711 calculates power at eachsampling time using the current and the voltage applied in real-timethrough the path {circle around (1)} or {circle around (2)}. The firstsignal control unit 711 compares a current power with a previous powerand performs a MPPT control operation for tracking a maximum power P1.Sequentially, the first signal control unit 711 outputs the determinedmaximum power P1 to the final power output unit 80.

The second signal control unit 712 calculates a maximum power P2 of thesecond solar cell row group GP2 in the same manner as the first signalcontrol unit 711 and then outputs the maximum power P2 to the finalpower output unit 80.

The final power output unit 80 selects the largest power among themaximum powers P1 and P2 respectively obtained from the first and secondsolar cell row groups GP1 and GP2 as a final power Pmax. The final poweroutput unit 80 then outputs the final power Pmax to a subsequent device.

In the embodiment of the invention, because the plurality of solar cellrows are divided into the plurality of solar cell row groups GP1 and GP2and the reduced amount of current in the solar cell row groups GP1 andGP2 is individually compensated by individually controlling the solarcell row groups GP1 and GP2, the output efficiency of the solar cellmodule 10 is improved.

Further, in the embodiment of the invention, the MPPT control operationis individually performed on the solar cell row groups GP1 and GP2, themaximum powers P1 and P2 are respectively tracked in the solar cell rowgroups GP1 and GP2, and the final power Pmax is selected among themaximum powers P1 and P2. Thus, the output efficiency of the solar cellmodule 10 is further improved.

FIG. 3 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention.Structures and components identical or equivalent to those illustratedin FIG. 2 are designated in FIG. 3 with the same reference numerals, anda further description may be briefly made or may be entirely omitted.

A photovoltaic power generation system 100 b shown in FIG. 3 has thesame structure as the photovoltaic power generation system 100 a shownin FIG. 2, except that the photovoltaic power generation system 100 bdoes not have a sensing unit and an amplification unit connected to eachof solar cell row groups GP1 and GP2. More specifically, thephotovoltaic power generation system 100 b shown in FIG. 3 includes afirst signal control unit 721 connected between a hole terminal (+) andan electron terminal (−) of the first solar cell row group GP1, and asecond signal control unit 722 connected between a hole terminal (+) andan electron terminal (−) of the second solar cell row group GP2.

An operation of the photovoltaic power generation system 100 b havingthe above-described structure is described below.

Similar to the photovoltaic power generation system 100 a shown in FIG.2, an operation of the first signal control unit 721 connected to thefirst solar cell row group GP1 is substantially the same as an operationof the second signal control unit 722 connected to the second solar cellrow group GP2. Therefore, only the operation of the first signal controlunit 721 is described in the embodiment of the invention, and a furtherdescription of the operation of the second signal control unit 722 maybe briefly made or may be entirely omitted.

When current and voltage are generated in the first solar cell row groupGP1 through operations of the solar cells 1 belonging to the first solarcell row group GP1, the current and the voltage are applied to the firstsignal control unit 721. Then, the first signal control unit 721converts the current and the voltage into digital type current anddigital type voltage.

Next, the first signal control unit 721 receives in real-time thedigital type current and voltage from the first solar cell row group GP1and performs the MPPT control operation described above with referenceto FIG. 2.

Accordingly, the first signal control unit 721 reads current and voltageat each sampling time using the currents and the voltages received inreal-time from the first solar cell row group GP1 and calculates powerat each sampling time. The first signal control unit 721 compares acurrent power with a previous power and calculates a maximum power P1 ofthe first solar cell row group GP1. The first signal control unit 721then outputs the maximum power P1 to a final power output unit 80.

The second signal control unit 722 calculates a maximum power P2 of thesecond solar cell row group GP2 in the same manner as the first signalcontrol unit 721 and then outputs the maximum power P2 to the finalpower output unit 80.

The final power output unit 80 selects the largest power among themaximum powers P1 and P2 respectively obtained from the first and secondsolar cell row groups GP1 and GP2 as a final power Pmax. The final poweroutput unit 80 then outputs the final power Pmax to a subsequent device.

In the embodiment of the invention, the MPPT control operation isindividually performed on the first and second solar cell row groups GP1and GP2, the maximum powers P1 and P2 are respectively tracked in thefirst and second solar cell row groups GP1 and GP2, and the final powerPmax is selected among the maximum powers P1 and P2. Thus, the outputefficiency of the solar cell module 10 is improved.

FIG. 4 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention.Structures and components identical or equivalent to those illustratedin FIGS. 3 and 4 are designated with the same reference numerals, and afurther description may be briefly made or may be entirely omitted.

A photovoltaic power generation system 100 c shown in FIG. 4 includes aplurality of signal control units 721 to 723 respectively connected to aplurality of solar cell modules 10 and a final power output unit 80connected to the plurality of signal control units 721 to 723.

The plurality of solar cell modules 10 to 30 form a solar cell panel130. As described above, each of solar cell modules 10 to 30 includes aplurality of solar cells that are arranged in a matrix structure and areconnected in series to one another

An operation of the photovoltaic power generation system 100 c havingthe above-described structure is described below.

Since operations of the first to third signal control units 721 to 723are substantially the same as one another, only the operation of thefirst signal control unit 721 is described in the embodiment of theinvention. A further description of the operations of the second andthird signal control units 722 and 723 may be briefly made or may beentirely omitted.

When a current and a voltage each having a corresponding magnitude areoutput from the first solar cell module 10 by operating the solar cellsincluded in the first solar cell module 10, the first signal controlunit 721 converts the current and the voltage output in real-time fromthe first solar cell module 10 into digital type current and digitaltype voltage. The first signal control unit 721 decides states of thecurrent and the voltage output in real-time from the first solar cellmodule 10.

Next, the first signal control unit 721 receives in real-time thecurrent and the voltage from the first solar cell module 10 and performsthe MPPT control operation based on the current and the voltage outputfrom the first solar cell module 10.

Accordingly, the first signal control unit 721 reads current and voltageat each sampling time using the current and the voltage received inreal-time from the first solar cell module 10 and calculates power ateach sampling time. The first signal control unit 721 compares a currentpower with a previous power and calculates a maximum power P1 of thefirst solar cell module 10. The first signal control unit 721 thenoutputs the maximum power P1 to a final power output unit 80.

The second and third signal control units 722 and 723 respectivelycalculate maximum powers P2 and P3 of the second and third solar cellmodules 10 in the same manner as the first signal control unit 721 andthen respectively output the maximum powers P2 and P3 to the final poweroutput unit 80.

The final power output unit 80 selects the largest power among themaximum powers P1 to P3 respectively obtained from the first to thirdsolar cell modules 10 to 30 as a final power Pmax. The final poweroutput unit 80 then outputs the final power Pmax to a subsequent device.

In the embodiment of the invention, the MPPT control operation isindividually performed on the first to third solar cell modules 10 to30, the maximum powers P1 to P3 are respectively tracked in the first tothird solar cell modules 10 to 30, and the final power Pmax is selectedamong the maximum powers P1 to P3. Thus, the output efficiencies of thesolar cell modules 10 to 30 are improved.

FIG. 5 is a schematic block diagram of a photovoltaic power generationsystem according to another example embodiment of the invention.Structures and components identical or equivalent to those illustratedin FIGS. 4 and 5 are designated with the same reference numerals, and afurther description may be briefly made or may be entirely omitted.

A photovoltaic power generation system 100 d shown in FIG. 5 includes aplurality of amplification units 331 to 333 respectively connected to aplurality of solar cell modules 10 to 30, a plurality of signal controlunits 721 to 723 respectively connected to the plurality ofamplification units 331 to 333, and a final power output unit 80connected to the plurality of signal control units 721 to 723.

An operation of the photovoltaic power generation system 100 d havingthe above-described structure is described below.

Since operations of the first to third signal control units 721 to 723are substantially the same as one another, only the operation of thefirst signal control unit 721 is described in the embodiment of theinvention. A further description of the operations of the second andthird signal control units 722 and 723 may be briefly made or may beentirely omitted.

When a current and a voltage each having a corresponding magnitude areoutput from the first solar cell module 10 by operating the solar cellsincluded in the first solar cell module 10, the first amplification unit331 amplifies in real-time the voltage output in real-time from thefirst solar cell module 10 to a previously determined magnitude andoutputs the amplified voltage to the first signal control unit 721. Thefirst signal control unit 721 receives in real-time the current from thefirst solar cell module 10.

Next, the first signal control unit 721 converts the current and thevoltage into digital type current and digital type voltage. The firstsignal control unit 721 decides states of the current and the voltageoutput in real-time from the first solar cell module 10.

Next, the first signal control unit 721 receives in real-time thecurrent and the voltage from the first solar cell module 10 and performsthe MPPT control operation based on the current and the voltage outputfrom the first solar cell module 10.

Accordingly, the first signal control unit 721 reads current and voltageat each sampling time using the currents and the voltages received inreal-time from the first solar cell module 10 and calculates a currentpower at each sampling time. The first signal control unit 721 comparesthe current power with a previous power and calculates a maximum powerP1 of the first solar cell module 10. The first signal control unit 721then outputs the maximum power P1 to the final power output unit 80.

The second and third signal control units 722 and 723 respectivelycalculate maximum powers P2 and P3 of the second solar cell module 20and third solar cell module 30, respectively, in the same manner as thefirst signal control unit 721 and then respectively output the maximumpowers P2 and P3 to the final power output unit 80.

The final power output unit 80 selects the largest power among themaximum powers P1 to P3 respectively obtained from the first to thirdsolar cell modules 10 to 30 as a final power Pmax. The final poweroutput unit 80 then outputs the final power Pmax to a subsequent device.

In the embodiment of the invention, because the voltage output from eachof the first to third solar cell modules 10 to 30 is amplified to thepredetermined magnitude, the power output from each of the first tothird solar cell modules 10 to 30 may increase. Hence, the amplifiedfinal power Pmax is output from the final power output unit 80. As aresult, the final power Pmax greater than power generated in a solarcell panel 130 may be obtained.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A photovoltaic power generation systemcomprising: a solar cell module including a plurality of solar cellgroups divided into groupings of the plurality of solar cell groups,each of the plurality of solar cell groups including at least one of onesolar cell row which a plurality of solar cells are electricallyconnected, and a plurality of signal control units connected to theplurality of solar cell groups, respectively, wherein the each of theplurality of signal control units track a maximum power based on thecurrent and the voltage output from each of the plurality of solar cellgroups and outputs the maximum power.
 2. The photovoltaic powergeneration system of claim 1, further comprising a plurality of sensingunits connected between each of the plurality of solar cell groups andeach of the plurality of signal control units, sense currents outputfrom the plurality of solar cell groups, and output the sensed currentsto the plurality of signal control units.
 3. The photovoltaic powergeneration system of claim 2, further comprising a plurality ofamplification units connected between each of the plurality of solarcell groups and each of the plurality of signal control units.
 4. Thephotovoltaic power generation system of claim 3, wherein each of theplurality of signal control units compares an amount of current sensedby each of the plurality of sensing units with a setting value, andapplies a control signal to a corresponding amplification unit of theplurality of amplification units, when the amount of current is lessthan the setting value, the corresponding amplification unitcorresponding to a sensing unit which outputs the amount of current lessthan the setting value, and the corresponding amplification unitamplifies a current input thereto and outputs the amplified current toan output terminal of a signal control unit.
 5. The photovoltaic powergeneration system of claim 1, further comprising a final power outputunit to be connected to the plurality of signal control units, whereinthe final power output unit selects the largest power among maximumpowers respectively applied to the plurality of signal control units.